An aerosol-type dispenser wherein the interior of the container is separated into isolated relatively fluid tight product and propellant compartments by a piston assembly comprising an upper relatively stiff shape retaining portion slidably mounted within the container and having on respective opposite...http://www.google.com/patents/US3819092?utm_source=gb-gplus-sharePatent US3819092 - Pressurized dispensers

An aerosol-type dispenser wherein the interior of the container is separated into isolated relatively fluid tight product and propellant compartments by a piston assembly comprising an upper relatively stiff shape retaining portion slidably mounted within the container and having on respective opposite sides substantially full area contact with the product and propellant and a depending flexible skirt anchored fluid tight within the lower interior of the container.

This invention relates to pressurized dispensing and particularly to pressurized dispensers of the type wherein a propellant acts through a piston or like follower to effect discharge of a foam product such as shaving cream.

The invention is particularly applicableto aerosoltype dispensers for producing a foam product such as shaving cream, wherein it is necessary or advisable to maintain the product separated from the propellant.

Dispensers have been proposed wherein the interior of the containeris separated into product and propellant compartments by a freely slidablepiston. There have been drawbacks in these dispensers due either to leak of propellant past the piston into the product, or to leak of product past the piston into the propellant compartment. Either is objectionable particularly in the dispensing of foam products. In the first instance propellant vapor usually collects around the product dispensing valve so that when the valve is actuated a non-homogeneous mixture of product and unblended propellant is discharged which, for example where the product is pressurized shaving cream, provides a product foam that is spluttery, dry and hard to spread on the face. Where product leaks into the propellant compartment it cannot be recovered and is wasted.

It has also been proposed to isolate the product in a sealed flexible bag-like enclosure defining the product compartment within the container, but this has been usually found to show poor product exhaustion. Similar difficulties in exhausting the product have been encountered where the propellant compartment is isolated within the container by a peripherally attached flexible diaphragm. In both of these instances the flexible bag or diaphragm provides a non-uniform follower action.

In the present invention the advantages of positive follower action and sealed isolation of the product and propellant compartments are provided, and this is a major object.

It is an important object of this invention to provide a novel dispensing container of the aerosol type wherein the product and propellant gas compartments are maintained in sealed isolation and wherein the main barrier wall between the compartments is relatively stiff and is slidably disposed within the container.

A further object of the invention is to provide a novel pressurized dispenser wherein the propellant gas compartment is defined within the product container by a relatively stiff cup-shaped upper section slidably mounted on the container inner wall and a depending substantially fluid tight flexible skirt section anchored to the lower end of the container.

Further objects will appear as the description proceeds in connection with the appended claims and the annexed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation in section showing a substantially empty aerosol type container embodying a preferred form of the'invention;

FIG. 2 is a side elevation in section similar to FIG. 1 but showing the pressurized container ready for use after the product and propellant have been incorporated;

FIG. 3 is a side elevation in section similar to FIGS. 1 and 2, and showing the relationship of parts when the product has been partially dispensed;

FIG. 4 is a side elevation like FIG. 3 but showing an embodiment wherein the piston assembly is differently formed and anchored;

FIG. 5 is a section on line 5-5 of FIG. 2 showing the piston assembly and;

FIG. 6 is a fragmentary section showing a method of attachment of the flexible piston skirt to the container wall. PREFERRED EMBODIMENTS:

Referring to FIGS. 1-3 and 5, an aerosol container of generally conventional size comprises a metal body 11 having a cylindrical side wall 12 upon the lower end of which'a metal bottom cover 13 is permanently secured, as by a conventional peripheral crimped joint 14. Cover 13 presents a convex surface within the container, as is known, for resistance to internal pressure.

Centrally cover 13 is formed with an aperture 15 as shown in FIG. 1 adapted to receive a soft rubber or like resilient seal plug 16 as shown in FIG. 2.

At its upper end the container continues as an inwardly and upwardly inclined annular end wall 17 that is secured to the top of side wall 12 by a conventional crimped joint 18. A valve support 19 is centrally secured to the inner periphery of wall member 17 by a conventional crimped joint 21.

Centrally member 19 is formed with an upright hollow tubular portion 23 mounting a discharge valve assembly 24. Valve 24 comprises a body 25 fixed within tube 23, and a resilient valve seat annulus 26 is peripherally clenched between the upper end of body 25 and an inturned flange 27 on the top of tube 23.

Bore 31 is open to the space 34 in the upper end of the container through an opening 35, and the upper end of bore 31 is normally sealed pressure tight due to engagement of the stem and valve seat.

The upper section of stem 28 is formed with a radial passage 36 that intersects a longitudinal passage 37. A dischargecontrol button 38 formed with an upwardly and laterally outwardly directed passage 39 open to stem passage 37 is fixed on stem 28 in spaced relation to flange 27.

The foregoing construction is more or less conventional. The metal container for example may be that disclosed in Moller et al. US. Pat. No. 3,471,059; and the valve may be for example the same as disclosed in Alplanalp US. Pat. No. 2,631,814. Alternatively the container walls and the end closures could be hard plastic units, suitably formed. The invention is mainly independent of the container construction or the type of discharge valve.

In general, when button 38 is displaced as by finger pressure toward the container body, stem 28 is displaced to uncover the outer end of radial passage 36 to place bore 31 in fluid communication with passages 37 and 39, and when the button is released spring 33 restores the stem to valve closed sealed position.

In the invention the interior of the container is separated into two compartments 34 and 40 by a piston assembly indicated at 41 and consisting essentially of a relatively stiff or hard upper end portion 42 and an collapsible flexible skirt 43. Compartment 34 is the product space above the piston assembly, and compartment 40 is the propellant receiving space.

The piston assembly upper end 42 is preferably a cup-shaped molded cap portion of polyethylene, polytetrafluorethylene or like plastic, that is adequately stiff and rigid for maintaining its shape under the pressures involved. Cap 42 has a smooth upper surface 44 peripherally merging at an annular curved corner 45 with a cylindrical side wall 46 that has a smooth sliding self lubricating fit with the cylindrical inner surface of container wall 12. The transverse area of cap 42 contacting the product in compartment 34 is substantially and effectively the same as that exposed to the propellant gas from below.

The flexible skirt 43 is an annulus having its upper end sealed fluid tight with the lower edge of cap wall 46. Skirt 43 may be an integral pleated, corrugated or similarly flexible extension of the more rigid cap, or it may be a collapsible tube of a suitable film thickness of tough gas impermeable plastic like polyvinyl chloride bonded fluid tight to the lower edge of cap 42. The lower edge of skirt 43 may be peripherally anchored with an annular fluid tight seal within the bottom cover joint 14. The propellant space 40 within the piston assembly is thussealed fluid tight and its contents isolated with respect to container space 34 above it. Space 34 is also fluid tight when the valve 24 is closed.

FIG. 1 shows that the piston assembly when fully extended may extend substantially the length of the container. In the disclosed embodiment the piston cap is recessed at 50 so that cap 42 may ascend to substantially exhaust all of product space 34. As shown, the piston cap may abut and be stopped by the container end wall short of closing opening 35. The body 11 and bottom cover 13, without the plug 16, are usually assembled with the piston assembly within the container body. In some embodiments plug 16 may be self-sealing rubber plug fixed in opening 15 for hollow needle insertion of propellant gas or gas forming liquid into space In any event, the completed filled and pressurized container will be essentially as shown in FIG. 2. The piston assembly 41 will be in compressed condition, the space 40 therewithin containing the propellant gas. Piston skirt 43 is collapsed as fully as possible to provide maximum product space 34, and added lengths of the collapsed skirt and the stiff side wall 46 of the piston cap is sufficient to insure that propellant space 40 is of adequate volume. The undersurface of cap 42 continuously provides the same desirably large area directly exposed to propellant pressure.

The product, liquid, powdered or otherwise fluent, is introduced into space 34 as through the opening in end wall 17 before member 19 is attached, and pressurized through the valve 24 as in some aerosol filling arrangements. Any conventional product introduction mode may be used.

Similarly the propellant may be conventionally introduced into space 47. For example a gas generating liquid may be introduced through opening 15 and sealed in by plug 16, or a gas generating liquid or gas may be introduced through a self-sealing plug in opening l5.

FIG. 4 illustrates an embodiment wherein the container is essentially the same as in FIGS. 1-3 and 5 but wherein skirt 43 is a separate member integrally bonded to the lower edge of piston cap wall 46 as on an annular joint 51, and wherein the lower end of the piston skirt 43 is a flexible transverse wall 52 integral with or bonded to seal plug 53. Plug 53 may be of selfsealing rubber. In this embodiment the propellant is sealed in space 54 within the piston assembly and never contacts container wall 12.

In the embodiment shown in FIG. 6, the lower periphery 57 of skirt 43 is anchored to the bottom wall of the container by an annular fluid tight adhesive joint 58. Otherwise the parts are as in FIGS. l-3.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters I Patent is:

What is claimed is:

l. A dispenser of the type wherein the interior of a cylindrical container is separated into product and propellant compartments with the propellant compartment containing fluid under pressure and being sealed fluid tight with respect to the product compartment, said container having a top end wall centrally mounting a manually operable normally closed valve for selective discharge from the product compartment, said valve having a body projecting into said product compartmentand having an inlet opening in the lower end of said body, characterized by a cup-shaped piston assembly within the container for separating and isolating said compartments, said piston assembly being composed of synthetic plastic material sufficiently stiff to maintain its shape under the internal pressures encountered in said container and having a transverse portion that extends across the entire area of said container to serve as the bottom of said product compartment and having a depending integral side wall in smooth sliding engagement with the internal cylindrical surface of said container, said transverse portion being formed with a central upwardly open recess and having on respective opposite sides substantially full area contact with the product in said product compartment and the propellant in said propellant compartment, and a depending collapsible flexible skirt extension of said piston assembly that is anchored at its lower end by a fluid tight connection to the lower interior of said container, said skirt being integrally bonded to the lower end of said piston assembly side wall and being of such effective length that during dispensing of the product said transverse portion of the piston assembly is capable of being displaced from its lowermost position wherein the product compartment is of maximum size to an upper position in abutment with the container top end wall, said recess being of such size as to so receive said valve body as to prevent said piston from closing said valve inlet opening when the piston abuts said container top end wall.

2. The dispenser defined in claim 1 wherein said piston assembly is composed of polyethylene.

3. The dispenser defined in claim 1, wherein said piston assembly skirt has its lower periphery secured around a fluid tight joint with the lower end of said container.